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Aluminum AK Lower

20K views 57 replies 26 participants last post by  Aum69 
#1 ·
Decided to try and build my own AK lower that will use AR trigger/safety/and grip. Doing this completely free hand using the PTS lower as a reference and a stripped colt AR lower. Props to real machinists out there, this is time consuming and tedious. I have the trigger area complete, going to work on the back end next where it connects to the stock. I will post pics each day, I plan on going till its done since it's snowing and I have little else to do. Not sure how long it will take but it doesn't matter, it's for fun.


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#2 ·
make me one:D
 
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#3 ·
Based on my experience with the APWR lower, the principle challenge will be fitment with the upper, specifically at the takedown captive pins, and more specifically at the receiving holes for these pins. I.e., the pins are captive in the lower receiver on the right side, drift through the tunnel in the upper or stock, and then insert into receiving holes on the left side of the lower. In the stock items, the pin tips wedge snuggly into these receiving holes. Joester's handguard, which is CNC milled, also achieves a tight fight. The APWR lower, though, is drilled just a little loose on the receiving holes. It's just enough to allow some play between the upper and lower. Play between the parts means uncontrolled vibration during firing.
 
#4 ·
Day 4, worked on the trigger area, grip and front pin location. It's coming together nicely and is more enjoyable as it starts to really take shape. I need to get my hands on a magpul AK mag before I start the mag well. Decided since it was their design to begin with that I will make my lower fit their mag and if any others happen to fit great, but I'm not going to try and make it universal.

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#7 ·
Day 6, worked on stepping up the sides where it goes from AR to ACR. I machined the inside of the lower too large in a couple areas not thinking far enough ahead how that would affect my exterior walls. I made a small hole in the back that I will have to weld shut and re machine. For a first time if that's my only hiccup I will be pleased. I also ordered an AK Pmag and will have to wait for it to arrive before going much farther.

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#8 ·
Day 7, worked on the sides a little more and pretty much done with the back. Threaded the hole for the grip bolt and started working on the magwell. Just made some basic cuts to get the shape while I'm waiting on the Pmag. Overall it's going well.

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#10 ·
Day 8, progress is slowing up a little as I work on the important details and finishing areas. I'm nervous about most of what I'm doing as I get farther along because it will be a lot of work lost if I mess up. I worked on the magwell most of the day, flared the edges out and worked on the front and back of the magwell. Still waiting on Pmag. Seems aim surplus is bogged down with a lot of orders.

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#11 ·
Day 8, progress is slowing up a little as I work on the important details and finishing areas. I'm nervous about most of what I'm doing as I get farther along because it will be a lot of work lost if I mess up. I worked on the magwell most of the day, flared the edges out and worked on the front and back of the magwell. Still waiting on Pmag. Seems aim surplus is bogged down with a lot of orders.

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Looks great Bossfoss. I only saw this thread a few days ago and I went back and read all of the previous posts. What are you using to machine the lower? A drill press and adjustable vice? Thanks for documenting the process and making me want one now. :)
 
#13 ·
Day 9ish, ended up going to UT for a day so I picked up an AK pmag while I was there since aim surplus is lagging. Got the pmag fitted to where rounds strip off correctly (hand cycling). I need to weld a small piece in the front to keep the mag from over inserting. Drilled out the takedown pins and drilled the mag release/catch pin. Going to need to fabricate a new longer release lever. The PTS one is too short. Needs to be metal anyway I figure.

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#14 ·
Day 10, fabricated the new release lever. Works great, mag locks in tightly. Need to weld on the over insertion piece, finish milling the sides around the magwell and drill selector/take down pin detents. Other than that it will just need sanding and polishing.

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#15 ·
Day 11, re profiled the magwell to make it shorter at the nose to match the hand gaurd takedown pin area. Also makes mag insertion easier due to the way AK mags hinge on the front and roll into place. Re flared the inside of the magwell and styled the sides of magwell. Drilled my selector detent as well. Only thing left to do is drill the takedown pin detents and weld the over insertion piece on the front.

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#17 ·
Day 13, Brown chicken brown cow! AK lower complete. Converted the PTS pins to AR style takedown and drilled holes in reciever for the springs. Polished and bead blasted to remove as many imperfections as I could. My Faxon 10.5 7.62x39 barrel showed up today, seems like a nice barrel I guess time will tell. I will get that fully together tomorrow hopefully. I realized I'm missing the extractor for Mikes bolt so I won't be able to test fire just yet, I'll see if I can get one by the end of the week. I haven't made up my mind if I'm going to try for a bolt catch, I need to spend some more time with it and see what I can do.

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#18 ·
Day 13, Brown chicken brown cow! AK lower complete. Converted the PTS pins to AR style takedown and drilled holes in reciever for the springs. Polished and bead blasted to remove as many imperfections as I could. My Faxon 10.5 7.62x39 barrel showed up today, seems like a nice barrel I guess time will tell. I will get that fully together tomorrow hopefully. I realized I'm missing the extractor for Mikes bolt so I won't be able to test fire just yet, I'll see if I can get one by the end of the week. I haven't made up my mind if I'm going to try for a bolt catch, I need to spend some more time with it and see what I can do.

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Looks awesome man, now we need a shop with a CNC to start building some!
 
#21 ·
Im considering finding a place just to see what it would take to make copies, I believe 68 is working on one now but it may just be a 5.56 version so Idk. I've never really thought about 6.8 and I don't know much about what it would take. If I do another one I will be trying to make a MP5 style one that will do 9mm using those mags. Although buying a mp5 parts kit and building the real thing sounds more fun to me than totally redesigning the ACR bolt for 9mm. I had a lot of fun doing it and it's cool to know I have a unicorn of sorts so who knows what's next.
 
#25 ·
Decided to modify my enhanced handguard to see if I could make it into something besides a paperweight. Easy to do if you wanted to do the same to yours. Just copy the existing holes and offset them on rail portions. I milled off the side picatinny rails as well because they were useless to me.

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#27 ·
Test fired today. Had short stroking issues. Peeled rounds off the mag fine which was good to see. Anybody have a SBR 7.62x39 that could share what gas port size they are running. I'm guessing it was my op rod more than anything but, it would be nice to make sure before I start drilling the port larger.
 
#32 ·
bossfoss , CONGRATS !! that's some damn fine work, love the detail in blending all the angles, really like the use of readily available AR parts , can you tell me by chance what you used for the mag catch spring ? -your fortune awaits if you build these , and I agree totally with the suggestion that 3D printing is the way to go here CNC is too costly , good luck
 
#34 ·
Thanks man, it was a fun challenge. I used the spring from the air soft version. It isn't quite strong enough to last a long time in my opinion though. When it goes I will have to find something stronger. Maybe a clothes pin spring would work.
 
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